1. Field of the Invention
The present general inventive concept relates to an image forming apparatus. More particularly, the present general inventive concept relates to a developing cartridge with an improved structure, an image forming apparatus having the same, and a maintenance method of a developing cartridge.
2. Description of the Related Art
Generally, image forming apparatuses such as laser printers, copiers, etc., form an electrostatic latent image on a photosensitive medium, supply toner to the electrostatic latent image so as to develop the electrostatic latent image into a toner image, and then transfer the toner image onto a printing medium, thereby performing a printing operation.
Nowadays, a developing cartridge, in which a photosensitive medium and a developing member to supply toner are associated as one unit, has been widely used so that maintenance and repair of the image forming apparatus become easy.
FIG. 1 is an exploded perspective view illustrating a conventional developing cartridge.
Referring to FIG. 1, a conventional developing cartridge 1 includes a lower frame 10 and an upper frame 20.
In the lower frame 10 is disposed a photosensitive medium 11 on which a laser beam emitted from a light exposure unit (not illustrated) forms an electrostatic latent image. A charging roller 13 that charges a surface of the photosensitive medium 11 by a predetermined voltage is disposed at a side of the photosensitive medium 11. Also, a developing roller 15 to supply the electrostatic latent image with toner is disposed to rotate in contact with the photosensitive medium 11 at a side of the charging roller 13. A toner regulating member 17 and a toner supplying roller 16 are disposed at a side of the developing roller 15. The toner supplying roller 16 supplies the developing roller 15 with toner which is stored in a toner storing space 18 of the lower frame 10. The toner regulating member 17 is disposed to be in contact with the developing roller 15 and regulates toner conveyed onto the developing roller 15 by the toner supplying roller 16 into a thin toner layer. In the lower frame 10, a used toner storing space 19 is disposed opposite to the toner storing space 18 with respect to the photosensitive medium 11. Therefore, used toner removed from the surface of the photosensitive medium 11 is stored in the used toner storing space 19.
The upper frame 20 is assembled on an upper side of the lower frame 10 and functions as a lid or a cover to close up the upper side of the lower frame 10. The upper frame 20 is provided with a laser beam opening 21 through which a laser beam emitted from the light exposure unit passes.
In the conventional developing cartridge 1 with the above-described structure, a toner image is formed on the photosensitive medium 11 during a printing operation. In other words, when receiving a printing order, a laser beam emitted from the light exposure unit is incident on the photosensitive medium 11 through the laser beam opening 21 so as to form an electrostatic latent image corresponding to printing data on the surface of the photosensitive medium 11. Then, the developing roller 15 supplies toner, which is supplied from the toner supplying roller 16, to the electrostatic latent image so as to develop the electrostatic latent image into a toner image. The toner image formed on the photosensitive medium 11 is transferred onto a printing medium by a transferring roller (not illustrated).
In the conventional developing cartridge 1, all parts used to form a toner image on the photosensitive medium 11, that is, the photosensitive medium 11, the charging roller 13, the developing roller 15, and the toner supplying roller 16 are disposed in the lower frame 10.
If all parts used to form toner images are disposed in one frame such as the lower frame 10, it is inconvenient to maintain and repair the developing cartridge 1.
For example, when any part such as the charging roller 13, a used toner cleaner, etc, is damaged, it gives low maintenance cost to replace only the damaged charging roller 13 or used toner cleaner. However, since the conventional developing cartridge 1 cannot replace only the charging roller 13 or the used toner cleaner, the whole developing cartridge 1 is required to be replaced. Therefore, the conventional image forming apparatus requires a lot of maintenance costs.
Furthermore, although the charging roller 13 or used toner cleaner can be replaced, the structure is complex so that users cannot replace there items themselves.